Exercise promotes IL‐6 release from legs in older men with minor response to unilateral immobilization

Abstract

Physical inactivity is a major contributor to low-grade systemic inflammation. Most of the studies characterizing interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) release from exercising legs have been done in young, healthy men, but studies on inactivity in older people are lacking. The impact of 14 days of one-leg immobilization (IM) on IL-6 and TNF-α release during exercise in comparison to the contralateral control (CON) leg was investigated. Fifteen healthy men (age 68.1 ± 1.1 year (mean ± SEM); BMI 27.0 ± 0.4 kg·m(2); VO2max 33.3 ± 1.6 ml·kg(‒1)·min(‒1)) performed 45 min of two-leg dynamic knee extensor exercise at 19.5 ± 0.9 W. Arterial and femoral venous blood samples from the CON and the IM legs were collected every 15 min during exercise, and thigh blood flow was measured with ultrasound Doppler. Arterial plasma IL-6 concentration increased with exercise (rest vs. 45 min, main effect p < .05). IL-6 release increased with exercise (rest vs. 30 min, main effect p < .05). Furthermore, IL-6 release was borderline (main effect, p = .085, effect size 0.28) higher in the IM leg compared to the CON leg (288 (95% CI: 213-373) vs. 220 (95% CI: 152-299) pg·min(‒1), respectively). There was no release of TNF-α in either leg and arterial concentrations remained unchanged during exercise (p > .05). In conclusion, exercise induces more pronounced IL-6 secretion in healthy older men. Two weeks of unilateral immobilization on the other hand had only a minor influence on IL-6 release. Neither immobilization nor exercise had an effect on TNF-α release across the working legs in older men.

Cytokine Responses to Acute Exercise in Healthy Older Adults: The Effect of Cardiorespiratory Fitness

“…Despite this, we observed no exercise-induced cytokine responses to exercise. These findings support the suggestion that acute cytokine responses to exercise may be blunted in older adults (Hamada et al, 2005 ; Reihmane et al, 2016 ) compared to previous observations in younger adults (Reihmane et al, 2013 ). Further studies comparing acute cytokine responses to short-term exercise in older and younger participant groups would help further clarify the effect of age on the inflammatory response to exercise.…”

“…The current study is the first to compare acute cytokine responses to exercise in participants with above average (37.4 ± 5.9 mL.kg −1 .min −1 ) and below average (22.6 ± 2.8 mL.kg −1 .min −1 ) cardiorespiratory fitness levels, relative to age-specific normative data (Stensvold et al, 2017 ). Our findings indicate that the blunted cytokine response to exercise previously reported among older adults (Hamada et al, 2005 ; Reihmane et al, 2016 ) is not likely to be due to low fitness levels.…”

“…In response to a short bout of exercise, acute increases in IL-6 have been proposed to suppress pro-inflammatory TNF-α (Starkie et al, 2003 ), and up-regulate anti-inflammatory cytokines such as IL-10 (Steensberg et al, 2003 ; Lira et al, 2009 ), creating an anti-inflammatory milieu for several hours after the cessation of exercise (Mendham et al, 2015 ). While this response is well established in young people, the response in older adults is more varied, with reports that the skeletal muscle (Hamada et al, 2005 ) and circulating (Reihmane et al, 2013 , 2016 ) cytokine responses to a single bout of exercise may be supressed compared with those observed in young participants.…”

Interventional strategies to combat muscle disuse atrophy in humans: focus on neuromuscular electrical stimulation and dietary protein

“…Because of a minor influence of systemic factors that could potentially influence muscle atrophy (122), leg immobilization represents a suitable model to study muscle loss caused by isolated disuse per se. In contrast, with the use of the bed rest model, muscle loss is possibly influenced by systemic factors that are activated due to whole body disuse.…”

The Impact of Acute and Chronic Exercise on Immunoglobulins and Cytokines in Elderly: Insights From a Critical Review of the Literature

“…Accordingly, the IL-6 release from working muscles after 60 min of workout is preserved in healthy, 70-year-old men (83) when a two-leg knee extensor exercise is performed without muscle damage. Reihmane et al (84) reported that 45 min of two-leg dynamic knee extensor exercise at 19.5 ± 0.9 W increases IL-6 release from rest to 30 min of exercise but was not higher than the resting level after 45 min of exercise. In addition, after isokinetic exercise, the expression of MCP-1, IL-8 and IL-6 (pro-inflammatory) increased substantially while, the expression of the antiinflammatory cytokines IL-4, IL28 and IL-13 increased only slightly (or not at all) after exercise (85).…”